JPH09229163A - Differential case and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a differential case which is of a light weight, and can maintain a stable function for a long period, by providing plural reinforcing ribs provided in the radial form on the outer peripheral surface, and to increase the strength, and a window to allow to process and assemble the inner side, as well as molding unitary the differential case with a non-ferrous metal material. SOLUTION: In this differential case 22 molded unitary by a non-ferrous metal material, especially an aluminum alloy, a pair of the left and the right journals 23L and 23R are formed separating an adequate interval, and axle penetrating holes 24L and 24R are formed to the journals 23L and 23R. The journals 23L and 23R are connected integral at the connection 25, and a window 26 is formed on the outer peripheral surface of the connection 25. This window 26 is connected to the inner space of the differential case 22 used for the processing, the assembling, and the like, of a differential gear which consists of a pair of pinions, and side gears. On the outer peripheral surface of the connection 25, plural reinforcing ribs 32 to increase the strength are formed in the radial form.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential case suitable as a differential for transmitting a driving force of an automobile engine to a wheel drive shaft, and more particularly to a differential case which can be reduced in weight and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, in an automobile or the like, the driving force of an engine is input to a transmission (transmission) to control the driving force of the engine, and the controlled driving force of the engine is required from an output shaft of the transmission. A driving force transmission device is input to a differential (differential device) called a differential via a propeller shaft (propulsion shaft) in accordance with the driving force, and transmits the driving force of the engine to the wheel drive shaft by the differential. ing.

FIG. 11 shows an example of a differential 1 used in such a conventional driving force transmission device for an automobile. The differential 1 is rotatably mounted inside a transmission case 3 of a transmission 2. The differential case 4 is provided. A differential gear 7 including a pair of pinion 5 and a side gear 6 is disposed inside the differential case 4, and each side gear 6 of the differential gear 7 has a rotational axis RL of the differential case 4 and A pair of wheel drive shafts 8 shown by imaginary lines in FIG. 11, for example, one ends of front wheel drive shafts are attached so that their axes coincide with each other. Further, a pinion shaft 9 is arranged inside the differential case 4. This pinion shaft 9
Is disposed inside the differential case 4 so as to be orthogonal to the rotation axis RL of the differential case 4, and inside the differential case 4 of the pinion shaft 9 in the vicinity of both end portions shown in the vertical direction in FIG. The pinions 5 are arranged so as to face each other with an appropriate interval.

On the outer peripheral portion of the differential case 4, an annular ring gear 10 has its axis centered on the rotation axis R of the differential case 4.
The ring gear 10 is coupled so as to withstand the transmission torque by a bolt 11 or a rivet (not shown) so as to match L, and the drive gear 13 attached to the output shaft 12 of the transmission 2 is attached to the outer peripheral surface of the ring gear 10. A tooth portion 14 that meshes with is formed.

That is, the driving force of the engine is input from the output shaft 12 of the transmission 2 to the ring gear 10 of the differential 1, whereby the ring gear 10 and the differential case 4 rotate integrally and are arranged inside the differential case 4. Wheel drive shaft 8 via differential gear 7
Is to be driven.

Generally, the differential case 4 is a part in which the differential gear 7 is mounted and the wheel drive shaft 8 is inserted, and the differential case 4 is rotated with respect to each other.
It is formed by casting a cast iron metal material having excellent lubricity, for example, spheroidal graphite cast iron (FCD55: JIS G5502).

The ring gear 10 has teeth 14 formed on the outer peripheral surface thereof so as to transmit the driving force of the engine input from the output shaft 12 of the transmission 2 to the differential case 4. Steel-based metal material that can withstand driving force, for example carburized steel (SCM420: JIS G
4105) and the like are forged.

Hereinafter, the conventional differential case will be described in detail with reference to FIGS. 12 to 16.

In the conventional differential case 4, a pair of left and right journal portions 15 formed in a substantially annular shape shown in the left-right direction in FIG. 14 are formed at appropriate intervals. The axis of the journal portion 15 is made to coincide with the rotation axis RL of the differential case 4, and each journal portion 15 is rotatable inside the transmission case 3 of the transmission 2 as shown in FIG. It is designed to be attached.

An axle through hole 16 through which one of the wheel drive shafts 8 (left wheel drive shaft, FIG. 11) can be inserted into one journal portion 15L shown on the left side in FIG. 14, for example.
L is formed, and in the other journal portion 16R shown on the right side in FIG. 14, for example, the other side of the wheel drive shaft 8 (right wheel drive shaft, FIG. 11) can be inserted into the axle through hole 16.
R is formed. Each axle through hole 16L, 16R
Are formed so that their respective axes coincide with each other, and the axes of the axle through-holes 16L and 16R coincide with the rotation axis RL of the differential case 4.

The respective journal portions 15L, 15R are connected by a cylindrical connecting portion 17 whose base end portion located in the central portion in the axial direction has an outer diameter larger than the outer diameter dimension of each journal portion 15L, 15R. As shown in FIG. 15, a pair of windows 18 are formed on the outer peripheral surface of the connecting portion 17 so as to penetrate the connecting portion 17 in the plate thickness direction. The window portion 18 is used for processing the mounting portion of the differential gear 7 (FIG. 11) arranged inside the differential case 4 and assembling the differential gear 7.

Further, a pair of upper and lower shaft mounting holes 19 shown in the upper and lower parts of FIG. 14 are formed substantially at the center of the connecting portion 17 in the axial direction so as to be orthogonal to the rotational axis RL of the differential case 4. The shaft center is formed so as to coincide with each other, and the pinion shaft 9 (FIG. 11) is mounted in the shaft mounting hole 19.

An annular flange portion 20 for attaching the ring gear 10 (FIG. 11) is formed near the right end portion of the outer peripheral surface of the connecting portion 17 in FIG. As shown in FIGS. 12, 15 and 16, the flange portion 20 has ten screw holes penetrating in the plate thickness direction so as to extend parallel to the rotation axis RL of the differential case 4. 21 are arranged at equal distances from the rotation axis RL of the differential case 4 by equal angles.

Such a conventional differential case 4 is formed by casting the above-mentioned cast iron-based metal material cast iron, for example, FCD55, by GDC (gravity casting) using a mold composed of a sand mold and a sand core (not shown). After that, the cast product is formed by subjecting the cast product to heat treatment such as normalizing and then finishing by machining.

[0015]

In recent years, high performance and energy saving have been demanded in automobiles and the like, and in order to achieve the high performance and energy saving, the weight of the automobile has been reduced. ing. And lighter cars,
The weight reduction of the differential 1 is required in order to save energy, and the weight reduction of the differential case 4 is required in order to reduce the weight of the differential 1.

In order to cope with such a reduction in the weight of the differential case 4, there has been proposed a differential case 4 made of a non-ferrous metal material that is lighter than a steel material, for example, aluminum (aluminum alloy).

However, if the conventional diff case 4 made of aluminum has the same shape as the diff case 4 made of a steel material, the rigidity of the connecting portion 17 in which the window 18 is formed is insufficient and the durability is improved. However, there is a problem in that it has a short life and cannot maintain a stable function for a long period of time.

In order to deal with such a problem, in the conventional differential case 4 made of aluminum, a structure without the window portion 18 is proposed, but such a case is formed inside the differential case 4. It is very difficult to process the mounting portion of the differential gear 7 and the differential gear 7 cannot be assembled and is not in practical use at present.

Therefore, in order to process the mounting portion of the differential gear 7 inside the differential case 4 which does not form the window 18 and to assemble the differential gear 7, the differential case 4 is attached to the rotational axis RL of the differential case 4.
A two-piece structure divided into two in a direction orthogonal to
It is proposed that the divided differential case 4 is connected by bolts or the like. However, in such a two-piece configuration, the number of parts increases, and a great deal of labor and time are required to manufacture the product, which is economical. The physical burden increases,
In order to secure the strength of the connecting portion of the differential case 4, the length of the differential case 4 in the direction of the rotation axis RL is increased so that the differential case 4
However, there was a problem in that

The present invention has been made in view of the above points, and it is an object of the present invention to provide a differential case which is light in weight and can maintain a stable function for a long period of time without increasing in size, and a manufacturing method thereof. To aim.

[0021]

In order to achieve the above-mentioned object, the features of the differential case according to the present invention as set forth in claim 1 are that the differential case is integrally molded with a non-ferrous metal material and is radially formed on the outer peripheral surface. It has a plurality of reinforcing ribs that are arranged to increase the strength and one window portion that is formed on the outer peripheral surface to allow internal processing and assembly. By adopting such a configuration, it is possible to integrally mold a plurality of reinforcing ribs that increase the strength and one window portion that allows internal processing and assembly, from a non-ferrous metal material.

The differential case of the present invention as set forth in claim 2 is characterized in that, in claim 1, a tapping hole for removing the core is formed at a portion substantially facing the window portion. There is a point. By adopting such a configuration, it is possible to easily form an internal space inside the differential case for surely processing the mounting portion of the differential gear and assembling the differential gear.

Further, the characteristics of the differential case of the present invention as set forth in claim 3 of the present invention are as defined in claim 1 or claim 2.
In the above, the non-ferrous metal material is an aluminum alloy, and the chemical composition thereof contains Si of 11.7% or more. By adopting such a configuration, the function as the differential case can be surely retained for a long period of time.

Further, a feature of the method for manufacturing a differential case according to the present invention as set forth in claim 4 is that a core capable of forming one window portion which enables internal processing and assembly is provided with high strength. A mold is formed by arranging a plurality of reinforcing ribs to be increased inside the main mold, and a non-ferrous metal material in a molten state is injected into the mold to form a casting, and then the casting is performed. The point is that the product is heat-treated and then finished. By adopting such a configuration, the differential case according to any one of claims 1 to 3 can be efficiently and reliably manufactured.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings. The same or corresponding components as those of the above-described conventional device are denoted by the same reference numerals in the drawings, and description thereof will be omitted.

1 to 5 show an example of an embodiment of a differential case according to the present invention, FIG. 1 is a front view, FIG. 2 is a left side view, and FIG. 3 is a C of FIG. 4 is a sectional view taken along line C, FIG. 4 is a sectional view taken along line DD of FIG. 1, FIG. 5 is a rear view, and FIG. 6 is a differential gear for a differential case according to the present invention. It is explanatory drawing which shows the principal part of an attachment state and the attachment state with respect to the transmission of the differential case which concerns on this invention.

As shown in FIGS. 1 to 5, the differential case 22 of this embodiment is integrally molded, and a pair of left and right substantially annular journal portions 23 shown in the left-right direction in FIG. 3 are appropriately formed. It is formed at intervals. Then, one journal portion 23L shown on the left side in FIG.
An axle through hole 24L through which one of the wheel drive shafts (not shown) (the left wheel drive shaft) can be inserted is formed in
The other journal portion 23R shown on the right side in FIG. 3 is formed with an axle through hole 24R into which the other of the wheel drive shafts (not shown) (right wheel drive shaft) can be inserted.
The axle through-holes 24L and 24R are formed so that their axes coincide with each other, and the journal portions 2
The axes of 3L and 23R are the rotational axes RL of the differential case 22.
It is formed so as to match.

Each of the journal portions 23L and 23R has a substantially cylindrical connecting portion 25 whose base end portion located in the central portion in the axial direction has an outer diameter larger than that of each journal portion 23L and 23R. Are connected together by
On the outer peripheral surface of the connecting portion 25, as shown in FIGS. 1 to 4, one window portion 26 is formed so as to penetrate the outer peripheral surface of the connecting portion 25 in the plate thickness direction. The window portion 26 is used for processing the mounting portion of the differential gear 7 including a pair of pinions 5 and a pair of left and right side gears 6 disposed inside the differential case 22 and assembling the differential gear 7 (FIG. 6). It is connected to the internal space of the differential case 22 used. In addition, it is preferable that the edge portion of the window portion 26 has a thick shape called a frame or the like in order to further improve strength (rigidity).

At a substantially central portion in the axial direction of the connecting portion 25,
A pair of upper and lower shaft mounting holes 27 shown in FIG. 3 so as to be orthogonal to the rotational axis RL of the differential case 22 are formed so that their respective axial centers coincide with each other. The pinion shaft 9 is attached to 27 (FIG. 6).

An annular flange portion 28 for attaching the ring gear 10 (FIG. 6) is formed near the right end portion of the outer peripheral surface of the connecting portion 25 in FIG. As shown in FIGS. 1, 4 and 5, ten screw holes 29 penetrating in the plate thickness direction so as to extend parallel to the rotation axis RL of the differential case 22 are formed in the flange case 28. 22 are arranged at equal distances from the rotation axis RL of 22 for equal angles. An annular bearing surface 31 with which the ring gear 10 (FIG. 6) abuts is formed on the flange surface 30 of the flange portion 28 shown on the right side in FIG. 3.

As shown in FIGS. 1 and 5, a plurality of reinforcing ribs 32 for increasing strength are radially provided on the outer peripheral surface of the connecting portion 25 from the rotation axis RL of the differential case 22 as shown in FIG. It is formed excluding the formation portion of the window portion 26, and the screw holes 29 are formed on the extension lines of the reinforcing ribs 32.

Further, as shown in FIGS. 2 and 4, on the outer peripheral surface of the connecting portion 25, two tapping holes 34 for detaching a core 33 used in the later-described manufacturing process are formed. They are formed so as to face each other.

The number of screw holes 29 and tap holes 34 provided in the connecting portion 25 can be increased or decreased according to the specifications and design concept of the differential case 22.

Further, the flange portion 28 is provided with a rivet hole (not shown) in place of the screw hole 29, so that the differential case 2
2 and the ring gear 10 may be connected by rivets.

FIG. 6 shows the mounting state of the differential gear 7 and the like to the differential case 22 and the mounting state of the differential case 22 to the transmission 2 of the present embodiment. The ring gear 10 for the differential case 22,
The mounting state of the differential gear 7 and the like and the mounting state of the differential case 22 to the transmission 2 are the same as those of the conventional example described above, and detailed description thereof will be omitted.

Next, a method of manufacturing the differential case 22 of this embodiment will be described with reference to FIG.

FIG. 7 is a process chart showing an example of the embodiment of the method for manufacturing a differential case according to the present invention in the order of steps.

As shown in FIG. 7, in the method of manufacturing the differential case 22 of the present embodiment, a casting step 35, a heat treatment step 36, and a finishing step 37 are performed in order.

Each of the above steps will be described in more detail.

In the casting step 35, a core 33, which will be described later, capable of forming the window portion 26 is disposed inside the main mold 38, and the mold 3 is obtained.
9 is formed, and a non-ferrous metal material in a molten state in this mold 39, an aluminum alloy described later in the present embodiment, is injected under high pressure and cast to perform squeeze casting (pressure 1000 Kg / cm 2 or more). Etc., is subjected to high-pressure casting, and the molten non-ferrous metal material is solidified inside the mold 39. Then, the casting is taken out from the mold 39, and the core 33
Is separated from the casting to obtain an integrally molded casting. In addition, the core 33 of the present embodiment
Is a separable assembly type as will be described later, so that the portion of the core 33 located inside the tapping hole 34 formed in the casting can be easily tapped from the outside toward the inside. It can be released from the mold. In addition,
The casting method may be high pressure casting such as pressure die casting, and is not particularly limited to the casting method of the present embodiment.

In the heat treatment step 36, the T
By performing heat treatment of 6 (quenching and tempering) or T7 (stabilization treatment after quenching), a heat-treated product with improved mechanical properties of the cast product is obtained.

In the finishing step 37, the heat-treated product is machined using a lathe, a milling machine, a grinder, or the like, and the journal portions 23L and 23R and the axle through holes 24 are formed.
1 and 5 are machined to form L, 24R, a shaft mounting hole 27, a mounting portion of a differential gear 7 (not shown), a screw hole 29 for mounting a ring gear, and a seat surface 31. The product (the differential case 22) is obtained.

The differential case 2 formed in this way
2, the differential gear 7 including the pinion 5 and the side gear 6 and the pinion shaft 9 to which the pinion 5 is attached through the single window portion 26 by the assembling process 40 shown in phantom in FIG. Bearings are attached to the outer periphery of each of the journal portions 23L and 23R while being attached inside (FIG. 6).

Next, the material of the differential case of this embodiment will be described.

The differential case 22 of the present embodiment is integrally molded by casting, and as the material of the differential case 22, a non-ferrous metal material which is lightweight and has excellent mechanical properties and which can be cast is used. As for the above, an aluminum alloy having chemical resistance of 11.7% or more, Mn of 0.6% or less, and Zn of 4.2 to 4.5% and having improved wear resistance is used.

Next, the mold used for manufacturing the differential case of this embodiment will be described with reference to FIGS. 8 to 10.

FIG. 8 is a vertical sectional view showing an essential part of a mold used for manufacturing the differential case according to the present invention in an assembled state, and FIG. 9 is an explanatory view showing a disassembled state of the core, and FIG.
FIG. 4 is an explanatory diagram showing a core phase alignment surface of a core.

As shown in FIG. 8, the mold 3 according to the present embodiment.
The reference numeral 9 corresponds to the differential case 22 by a main mold (mold) 38 made of metal and a core (storage core) 33 made of metal that is removably arranged inside the main mold 38. The cavity 41 having a predetermined shape is formed. The main mold 38 has a fixed mold 38A shown on the right side in FIG. 8 and a movable mold 38B shown on the left side in FIG.
The movable die 38B is separated from the fixed die 38A, and the gate 42 is formed below the contact surface between the fixed die 38A and the movable die 38B. Further, the main mold 38 is provided with a plurality of rib forming portions 47 for forming the reinforcing ribs 32.

As shown in FIG. 9, the core 33 is formed by cores 33A, 33B, 33C and 33D which are divided into four parts in the left-right direction, and each core 33A, 33B, 33C,
As shown by the double-headed arrow in FIG. 9, two pieces of 33D which are adjacent to each other can be attached to and detached from each other. As shown in FIG. 8, when the cavity 41 is formed in the central portion of the left surface of the core 33A shown on the leftmost side in FIG. 9, the movable die 38B is fitted to form the axial mating surface. A concave portion 43 is formed, and when the cavity 41 is formed in the center portion of the right surface as shown in FIG.
A right recessed portion 44 is formed by fitting with and serving as an axially fixed surface. Further, the three cores 3 shown on the right side in FIG.
3B, 33C and 33D are fitted with the fixed mold 38A when the cavity 41 is formed as shown in FIG. Further, the core 3 shown on the rightmost side in FIG.
A window forming portion 45 for forming the window portion 26 is formed on the upper portion of the core 33C located on the left side of the 3D, and two projecting portions for forming the tapping hole 34 (only one is shown in the figure. ) 4
6 is formed below. The upper surface and the right surface of the window forming portion 45 are fitted with the fixed die 38A to form an axial fixed surface when the cavity 41 is formed as shown in FIG.
The tip of the protrusion 46 (specifically, the outer peripheral surface on the tip side) is shown in FIG.
When the cavity 41 is formed as shown in FIG.
8A is fitted to form an axial fixed surface. In addition, the front surface of the window forming portion 45 in FIG. 9 and the back surface (not shown) and the tip portion of the protrusion 46 (specifically, the outer peripheral surface on the tip side) form a cavity 41 as indicated by a thick arrow in FIG. In this case, it is fitted with the fixed die 38A to form a core phase direction fixed mating surface.

When the core 33 is to be removed from the internal space of the casting, the tip of the projection 46 of the core 33C fitted in the tapping hole 34 of the cast differential case 22 is tapped from the outside toward the inside. As a result, first, the core 33C having the window forming portion 45 is easily separated from the adjacent cores 33B and 33D through the window 26 of the cast differential case 22 and the outside of the internal space of the cast differential case 22. Can be removed (disengaged). Then, the core 3 having the window forming portion 45 from the inside of the cast differential case 22.
By removing 3C, the remaining cores 33B, 33
The D and 33A can be easily taken out through the window portion 26 of the differential case 22. That is, differential case 2
The maximum outer diameter that forms the inner space of No. 2 is the symbol W in FIG.
The width dimension of the window portion 26 of the differential case 22 shown in FIG. 2 is made equal to or slightly smaller than that of the window portion 26, and the thickness dimension of the core 33C having the window forming portion 45 shown by symbol h in FIG.
It is preferable that the height dimension of the window portion 26 of the differential case 22 indicated by the symbol H is equal to or slightly smaller than the height dimension.
Then, the surfaces of the cores 33A, 33B, 33C, and 33D that are adjacent to each other are provided with draft angles for easily separating the cores 33A, 33B, 33C, and 33D from the internal space of the differential case 22. It is preferably formed.

According to the core 33 having such a structure, the core 33 can be easily taken out from the inside of the cast differential case 22, and the core 33 is made of metal, so that the core 33 is not damaged easily and can be used a plurality of times. Since it can endure the use of the differential case 22, it is possible to surely reduce the total economical burden when mass-producing the differential case 22 as compared with the case where the sand core is formed for each casting. Moreover, although the core 33 is made of resin, the durability is inferior to that of the core 33 made of a metal material,
The weight can be reduced to improve the handling property, and the core can be recycled to reduce environmental pollution.

Next, the operation of this embodiment having the above-described structure will be described.

When the durability performances of the differential case 22 of the present embodiment and the conventional differential case 4 were evaluated, it was found that both of them can maintain a stable function for a long period of time. That is, the differential case 22 made by high pressure casting the aluminum alloy of the present embodiment has the same function as the conventional differential case 4.

The differential case 22 of the present embodiment formed by the manufacturing method of the present embodiment is integrally molded without being divided by casting a high-strength aluminum alloy, so that it does not increase in size. Since it is possible to surely reduce the weight and it is not necessary to divide the diff case 22, there is no need for an assembly process when dividing the diff case 22 into a conventional two-piece configuration, and the diff case 22 is smaller than that in the conventional case. It is possible to simplify the manufacturing process, surely improve the production efficiency, and surely reduce the economic burden.

Further, by forming the plurality of reinforcing ribs 32 and one window portion 26 using the aluminum alloy of the present embodiment, the strength (rigidity) of the differential case 22 is properly maintained, and it can be maintained for a long period of time. The stable function of the differential case 22 can be reliably retained.

Further, since the window portion 26 is formed in the differential case 22 of this embodiment, the mounting portion of the differential gear 7 with respect to the internal space of the differential case 22 and the assembly of the differential gear 7 are surely performed. You can

Furthermore, the differential case 2 of the present embodiment
A tapping hole 34 for taking out the core 33 is formed at a position substantially opposite to the window portion 26 in the No. 2, and the tapping hole 34 is formed.
A plurality of cores 33A for forming the internal space of the cast differential case 22 by hitting the core 33 through the
The core 33 made of 33B, 33C and 33D can be easily removed from the internal space of the cast differential case 22.

According to the differential case 22 of this embodiment, the differential case 2 made of an aluminum alloy is used.
Secondly, by fastening the ring gear 10 made of a cast iron metal material with the bolts 11, the soft differential case 22 functions as a cushion at the time of fastening, and it is possible to prevent loosening after fastening, which is a secondary effect. Also plays.

Further, the present invention is not limited to the above-mentioned embodiment, but can be modified as necessary.

[0060]

As described above, according to the differential case and the method of manufacturing the same of the present invention, a plurality of reinforcing ribs radially arranged on the outer peripheral surface to increase the strength by casting a non-ferrous metal material, and the outer periphery. One window part that is formed on the surface and allows internal processing and assembly is integrally molded, so that the differential case does not become large, is lightweight, and maintains a stable function for a long period of time. In addition, the production efficiency can be surely improved, and the economical burden can be surely reduced, which is an extremely excellent effect.

[Brief description of drawings]

FIG. 1 is a front view showing an example of an embodiment of a differential case according to the present invention.

FIG. 2 is a left side view of FIG. 1;

FIG. 3 is a cross-sectional view taken along line C-C in FIG.

4 is a cross-sectional view taken along the line DD of FIG.

FIG. 5 is a rear view of FIG. 1;

FIG. 6 is an explanatory view showing a main part of an installed state of a differential gear and the like to a differential case according to the present invention and an installed state of a differential case according to the present invention to a transmission.

FIG. 7 is a process diagram showing an example of an embodiment of a method for manufacturing a differential case according to the present invention in process order.

FIG. 8 is a vertical cross-sectional view showing a main part in an assembled state of a mold used for manufacturing the differential case according to the present invention.

FIG. 9 is an explanatory view showing a disassembled state of the core of the mold used for manufacturing the differential case according to the present invention.

FIG. 10 is an explanatory view showing a core alignment direction surface of a core of a mold used for manufacturing the differential case according to the present invention.

FIG. 11 is an explanatory view showing a main part of a differential used in a conventional vehicle driving force transmission device.

FIG. 12 is a front view showing a conventional differential case.

13 is a left side view of FIG.

14 is a sectional view taken along the line AA of FIG.

FIG. 15 is a sectional view taken along line BB of FIG.

16 is a rear view of FIG.

[Explanation of symbols]

 22 differential case 25 connecting part 26 window part 32 reinforcing rib 33, 33A, 33B, 33C, 33D core 34 tapping hole 35 casting process 36 heat treatment process 37 finishing process process 38 main mold 39 mold RL rotating shaft center (of the differential case)

Claims (4)

[Claims] 1. A plurality of reinforcing ribs which are integrally formed of a non-ferrous metal material and are radially arranged on the outer peripheral surface to increase the strength, and one window formed on the outer peripheral surface to enable internal processing and assembly. A differential case having a section. 2. The differential case according to claim 1, wherein a tapping hole for removing the core is formed in a portion substantially facing the window portion. 3. The differential case according to claim 1, wherein the non-ferrous metal material is an aluminum alloy, and the chemical composition thereof contains Si in an amount of 11.7% or more. 4. A mold is formed by arranging a core capable of forming one window portion for enabling internal processing and assembly inside a main mold capable of forming a plurality of reinforcing ribs for increasing strength. Then, a cast product is formed by injecting a non-ferrous metal material in a molten state into the mold, and then the cast product is heat-treated and then finish-processed.